Dr Kennedy on Pol '/ thing (Jrauite in India. 281 



Art. XVIII. — Notice respecting- the Working and Polishing 

 of Granite in India. In a Letter to the Editor, from 

 Alexander Kennedy, M. D. F. R. S. E. 



Dear Sir, 



You will probably recollect, that when the " Notices regard- 

 ing the Working and Polishing of Granite, by the Natives 

 of India, 11 appeared in the Edinburgh Philosophical Journal, 

 No. viii. p. 849, you then inquired whether any colouring 

 material was mixed with the lac and corundum, and which 

 would account for the black colour acquired by the granite in 

 the process of polishing. I could then only say, that though 

 I had frequently seen the process performed, and had also 

 witnessed the preparation of the ingredients, I had never 

 seen any colouring material mixed with them. I neverthe- 

 less set on foot an inquiry, by writing to a friend, who I 

 knew could easily ascertain the point from the native work- 

 men. It happened to be a subject with which lie was himself 

 well acquainted, and, in his reply, after mentioning that the 

 granite is first brought to a smooth surface by being rubbed 

 in the manner usual with masons, with part of its own sub- 

 stance and water, he adds, thai, in the process of polishing, 

 which was the object of my inquiries, " no colouring material 

 is used. 11 



I perfectly recollect, that, when the whole of this process 

 was performed under my own eye, the granite, after having 

 been smoothed with its own substance, retained its own co- 

 lour and appearance, having then acquired no part of the 

 black colour which it afterwards got under the lac and corun- 

 dum, and as to the origin of which we are still as much in the 

 dark as formerly. 



There seems good reason for believing, that the polish 

 which the stone thus acquires endures for ages. It is this 

 material which is so often seen used as black monumental 

 slabs, &c. in the Mussulman burying-grounds in India, and 

 of which also the pilasters, cornices, and other ornaments 

 of the mausolea, erected over their princes and great men, 



